Fruit Development Period Research Articles

Changes in the cell wall during fruit development and ripening in Fragaria vesca

Although fruit expansion during ripening has been extensively studied, the structural and metabolic mechanisms remain largely unknown. Here, we report the critical roles of cell separation and cell wall metabolism in the coordinated regulation of fruit expansion in Fragaria vesca. Anatomical observations indicated that a syndrome of cell separation occurred from the very earliest stage of fruit set. Cell separation led to an increase in apoplastic space, and the time course of this increase coincided with the period of fruit development and ripening. Moreover, massive cellulose disassembly occurred when cells were fully separated, which coincided with the expansion of cell and fruit volume. Consistent with the anatomical observations, both histochemistry and composition analysis indicated correlations between cell separation and the cell wall metabolism. These observations suggest that cell separation, cell elongation and cell wall disassembly occur simultaneously during fruit ripening in Fragaria vesca.

Effects of supplemental lighting during the period of rapid fruit development on the growth, yield, and energy use efficiency in strawberry plant production

Effects of supplemental lighting during the period of rapid fruit development on the growth, yield, and energy use efficiency in strawberry plant production

Variation in nutrients during the fruit development of Daisy tangerine

Seasonal progression in the nutritional concentration of fruit peel, pulp and leaves of Daisy tangerine cultivar were evaluated during fruit development period. Marked variations in nutritional content during specific fruit developmental stages were observed. Overall, leaves were the main sight of nutrient accumulation than fruit parts and their concentration was increased with the advancement in fruit maturity. The general order of abundance of macro and micronutrients in leaves was calcium (Ca)>nitrogen (N)>potassium (K)>magnesium (Mg)>phosphorus (P) and iron (Fe)>manganese (Mn)>zinc (Zn)>copper (Cu) respectively. Overall, P and K were higher in the pulp, while most of the micronutrients registered greater accumulation in the peel. However, in case of N, almost equal distribution was observed in peel and pulp of Daisy fruits. Leaf nutrient showed a strong association with peel, pulp and dry matter accumulation.

The Effect of Rainfall on Yellow Crude on Mangosis Fruit (Garciniamangostana L.)

The research was carried out through case studies at six locations of mangosteen production centers in West Sumatra during the 2018 harvest season. The results showed that mangosteen fruit damage by yellow sap was distinguished from yellow sap in exocarp and endocarp with varying percentages between research locations. There was no correlation between yellow sap in exocarp and endocarp (r=0.0656). Yellow sap in exocarp and endocarp correlate with rainy days. The intensity of rainfall during the fruit development period does not correlate with yellow latex in the endocarp but the fluctuation in rainfall is very influential. Yellow sap at the lowest endocarp (15%) was found at the location of Station-5 with the lowest rainy day (44 days) and low rainfall fluctuations (40-240 mm/month) and the highest (47%) at Station-3 (104 days rain and rainfall fluctuations 96-512 mm/month). The Station-4 area with lower rainy days (80 days) but has high rainfall fluctuations (73-954 mm/month) also shows yellow latex at a higher endocarp (35%) compared to other locations. Yellow gum at the lowest exocarp (32%) found in Station-2 (63 rainy days, 00 m asl) and highest (69%) in Station-6 (94 rainy days, 490 m asl). Effect of rainy days and altitude on the sap yellow on the skin of the fruit can be explained through its relationship with environmental conditions needed for the proliferation of insects that cause yellow sap on the mangosteen rind.

Genetic progress of the peach breeding program of Embrapa over 16 years

Abstract The peach breeding program of the Brazilian Agricultural Research Corporation (Embrapa), addressing the adaptation to mild winter conditions, is one of the largest in the world and maintains a germplasm collection of nearly 900 accessions. The objective was to estimate the genetic progress in fruit weight (FW) and fruit development period (FDP) resulting from the above program, by analyzing data records of 16 years (2000 - 2015) of 65 genotypes. Based on samples of ≥ 10 fruits, the mean annual FW (in g) and FDP (in number of days) from full flowering to harvest were determined. In the 16 years, the gain in FDP consisted of respective reductions of about -12.8, -3.3, -2.8 days for canning peach, fresh peach and nectarine. However, the genetic progress in fruit weight was 5.3, 1.4 and -17.9 g fruit-1 for canning peach, fresh peach and nectarine, respectively.

Targeted Proteomics Allows Quantification of Ethylene Receptors and Reveals SlETR3 Accumulation in Never-Ripe Tomatoes.

Ethylene regulates fruit ripening and several plant functions (germination, plant growth, plant-microbe interactions). Protein quantification of ethylene receptors (ETRs) is essential to study their functions, but is impaired by low resolution tools such as antibodies that are mostly nonspecific, or the lack of sensitivity of shotgun proteomic approaches. We developed a targeted proteomic method, to quantify low-abundance proteins such as ETRs, and coupled this to mRNAs analyses, in two tomato lines: Wild Type (WT) and Never-Ripe (NR) which is insensitive to ethylene because of a gain-of-function mutation in ETR3. We obtained mRNA and protein abundance profiles for each ETR over the fruit development period. Despite a limiting number of replicates, we propose Pearson correlations between mRNA and protein profiles as interesting indicators to discriminate the two genotypes: such correlations are mostly positive in the WT and are affected by the NR mutation. The influence of putative post-transcriptional and post-translational changes are discussed. In NR fruits, the observed accumulation of the mutated ETR3 protein between ripening stages (Mature Green and Breaker + 8 days) may be a cause of NR tomatoes to stay orange. The label-free quantitative proteomics analysis of membrane proteins, concomitant to Parallel Reaction Monitoring analysis, may be a resource to study changes over tomato fruit development. These results could lead to studies about ETR subfunctions and interconnections over fruit development. Variations of RNA-protein correlations may open new fields of research in ETR regulation. Finally, similar approaches may be developed to study ETRs in whole plant development and plant-microorganism interactions.

Changes in catechin contents and expression of catechin biosynthesis-associated genes during early cucumber fruit development

Cucumber (Cucumis sativus L.), a biologically, agriculturally, and economically important vegetable crop consumed worldwide. Catechins (Cs) are the main astringent substances that affect the oral sensory quality of cucumber fruit, and they exhibit potential human health benefits in the amelioration of chronic diseases. However, little is known about the primary components of Cs or their regulatory mechanisms in cucumber. In this study, dynamic changes in C levels and the expression patterns of C-related genes in the peel and flesh of cucumber inbred line ‘YB’, which is strongly astringent during the early fruit development period, were examined. Only three types of Cs, gallocatechin, C and epigallocatechin gallate, were detectable in cucumber fruit, and their contents decreased with fruit development. Gallocatechin was the major C and was present in significantly greater concentrations in peel than in flesh. The expression profiles of 38 genes related to C biosynthesis were investigated by qRT-PCR. We hypothesized that CsPAL3, CsPAL5, CsC4H1, Cs4CL2, CsCHS2, CsCHI2, CsDFR2, CsF3H3, and CsANS are the important C biosynthesis regulators in cucumber fruit. The isolation of genes encoding biosynthetic enzymes provides important molecular resources for further genetic manipulations of C biosynthesis in cucumber.

Refining the Genomic Region Containing a Major Locus Controlling Fruit Maturity in Peach

Maturity date (MD), defined as the duration between the first calendar day of the year and maturity, and fruit development period (FDP), defined as the duration between full bloom and maturity, are highly variable in peach [Prunus persica (L.) Batsch]. There is a need to discover molecular markers associated with these traits in order to enhance the efficiency and reliability of breeding for extending the harvest season in peach. An association mapping population consisting of 132 peach accessions was phenotypically evaluated for MD and FDP, and genotypically characterized using the genotyping-by-sequencing (GBS) approach. The phenotypic and genotypic data collected were used to conduct a genome-wide association study (GWAS). The GWAS identified three SNPs on chromosome 4 that are significantly associated with both FDP and MD. These three SNPs covered a region of 43,067 bp; we referred to this region as the MD/FDP locus. Seven genes were identified in the MD/FDP locus. One or more of these genes is believed to regulate some aspect of maturity in peach. The data reported here is expected to aid in marker-assisted seedling selection (MASS) targeted towards widening peach germplasm for maturity, particularly early maturity.

Genome-wide Association Analysis of Red Flesh Character Based on Resequencing Approach in Peach

Anthocyanins are important molecules that are responsible for fruit color formation and are also beneficial to human health. To date, numerous structural and regulatory genes associated with anthocyanin biosynthesis in peach (Prunus persica) have been reported based on linkage analysis. In this study, we sought to identify further genes associated with anthocyanin content in peach by conducting a genome-wide association analysis of 129 peach accessions to detect markers associated with the trait. Significant association signals were detected when anthocyanin content was considered a qualitative character but not when it was considered a quantitative trait. We detected an association region located between 11.7 and 13.1 Mb in chromosome 1, a region in which only 133 of 146 genes have previously been functionally annotated. Gene ontology annotation of the genes in this region showed that membrane-associated genes (including one gene encoding a chloride channel protein and 17 sugar transport/carrier-associated genes) were significantly enriched, and we focused on these in subsequent analyses. Based on in vitro induction of anthocyanins in fruit flesh using different exogenously applied sugars and subsequent culture, we found that the expression level of 3 of the 18 membrane-associated genes, Prupe.1G156300, Prupe.1G156900, and Prupe.1G157000, increased during induction treatment. Furthermore, during the fruit development period of a white-fleshed and a red-fleshed peach cultivar, the expression of one gene encoding a transmembrane sugar transport protein was observed to be positively correlated with anthocyanin biosynthesis. These results will facilitate understanding of the molecular mechanism of anthocyanin biosynthesis in peach.

Effects of multiple times of topdressing nitrogen application under equal level on utilization and distribution characteristics of 15N and 13C in winter jujube

We explored the effects of multiple times of topdressing nitrogen application under equal level on the characteristics of absorption, utilization, accumulation, and distribution of 15N and 13C in four-year-old potted winter jujube during fruit developmental periods using the stable isotope tra-cer technology. The results showed that with the increases of nitrogen application times, the 15N derived from fertilizer (Ndff) in each organ significantly increased at the fruit maturity. The distribution rates of 15N in reproductive organ (fruit) and vegetative organs (leaf, deciduous spur, new branch, and fine root) were highest under four-time application, and lowest under one-time application. The opposite pattern was observed in storage organs (trunk, perennial branch, and coarse root). The 15N utilization rate under four-time application was 27.4% and 15.5% higher than one-time and two-time application, respectively. The more times N being applied, the more total N content and 15N absorption amount of plant. Soil 15N abundance and total N content continued to drop under one-time application and increased at the beginning and then declined with the time under two-time application. The relatively stable soil 15N abundance and total N content appeared in four-time application, which was significantly higher than those in the other treatments in later treatment stages. The chlorophyll content, leaf nitrogen content and photosynthetic rate displayed an order of four-time application > two-time application > one-time application during fruit white-mature period to fruit harvest period. The accumulation and distribution of 13C varied across different treatments. Increasing nitrogen application times would promote more 13C being transported to fruit and storage organs but decrease that in annual vegetative organs. Our findings indicated that four-time nitrogen application could enhance and optimize the accumulation and distribution of photosynthetic products by ensuring steady and adequate supply of nitrogen and improving the absorption and utilization of nitrogen during fruit development period, which facilitates the growth, yield and quality of winter jujube.

Light and Temperature Independently Influence Methoxypyrazine Content of Vitis vinifera (cv. Cabernet Sauvignon) Berries

Methoxypyrazines (MPs) are fruit-derived extractable compounds that contribute to cultivar-specific aroma traits in wine, and greater concentrations can contribute to unpleasant vegetative aromas. Both light exposure and temperature have been reported to influence MP content in developing wine grapes, but individual effects of light and temperature are confounded. A novel method of manipulating light exposure with light-emitting diodes (LEDs) was used to impose light treatments with little or no effect on cluster temperature. Three treatments were imposed on developing fruit of Vitis vinifera (cv. Cabernet Sauvignon): 1) clusters exposed to direct sunlight, 2) clusters shaded by the grapevine canopy, and 3) clusters shaded by the canopy and exposed to supplemental LED light. Experiments were conducted over 3 years across pre- and postveraison periods of fruit development. A second experiment imposed the same light exposure treatments to ripening clusters on vines experiencing continual shoot growth during the postveraison period. Light exposure reduced 3-isobutyl-2-methoxypyrazine (IBMP) concentration of developing grape berries in the preveraison period independently of berry heating from solar radiation. Berry IBMP responded less to postveraison light levels, except on vines with active shoot growth, suggesting IBMP synthesis was continued during active vine growth but was suppressed by light. An inverse relationship of growing degree days (GDDs) with berry IBMP was observed, indicating high temperatures also reduce berry IBMP concentration. Response to temperature could result from either radiant heating of light-exposed clusters or from high ambient air temperature. Canopy management should consider the impact of both light and temperature on IBMP, and vine management practices should be adjusted appropriately to regional growing conditions and grape cultivars.

Altered development, quality and sink strength in asynchronous maturing fruits produced from the two-sequence female flowers inflorescence/cluster of ‘Yu Her Pau’ litchi

‘Yu Her Pau’ is one of the most dominant litchi (Litchi chinensis Sonn.) cultivars grown in Taiwan and China. However, the extremely large inflorescences often result in the production of early- and late- flowering female flowers (“two-sequence inflorescence”), thereby leading to the production of late-maturing fruit within the same cluster. This asynchronous maturity, often being regarded as a nuisance by growers and the impact of this trait requires further clarity. To document the alteration of growth and characteristics of fruits that mature asynchronously inside a cluster, 10-year-old field grown plants were used in the present study. Four categories of fruit: early- or late-maturing fruit in the presence of single cluster; and early- or late-maturing fruit in the presence of two-sequence cluster on trees were selected. The fruit growth curves and patterns, liquid endosperm retention in the embryo sac, primary (apparent) sink strength quantity and harvested quality were analyzed. The accumulated heat unit from fruit set to maturity was estimated. Flowering dates were noted to be three weeks apart, whereas harvest dates were noted to be only one week apart between the early- and late-maturing fruit because of the two-week longer maturity period of the early-maturing fruit. All categories of fruit exhibited single sigmoid curve and have commercial value at harvest. Early-maturing fruit from the early-maturing two-sequence inflorescence were approximately 50% heavier and matured two weeks earlier than the late-maturing fruit and exhibited significantly higher quality. The larger fruit from the early-maturing two-sequence clusters was associated with smaller seeds, higher absolute and relative fruit growth rates, longer fruit development periods in response to lower air temperatures pertaining at that time, greater primary sink strength quantity, longer retention of liquid endosperm, and higher accumulated heat units that were amassed during the pulp growth stage. In the meantime, the earlier dissipating of liquid endosperm in late-maturing fruit and in early-maturing two-sequence fruit was associated with decreased seed size. Late-maturing fruit in two-sequence clusters increased the primary sink strength quantity of early-maturing fruit in the same cluster. The results from our research should prompt a re-assessment of the physiological significance of the second-sequence of female flowers in litchi cultivars with extremely large inflorescence.

Overexpression of PpSnRK1α in Tomato Promotes Fruit Ripening by Enhancing RIPENING INHIBITOR Regulation Pathway.

As a conserved kinase complex, sucrose non-fermenting-1-related protein kinase 1 (SnRK1) is a major regulator of plant growth and development. In our previous study, overexpression of MhSnRK1 in tomato (Solanum lycopersicum L.) modified fruit maturation: the transgenic fruit ripened earlier than the wild type (WT). However, the mechanism by which fruit maturation is regulated by SnRK1 is not clear; therefore, the test materials used were the transgenic tomato lines (OE-1, OE-3, and OE-4) overexpressing the coding gene of peach [Prunus persica (L.) Batsch] SNF1-related kinase α subunit (PpSnRK1α). The activity of SnRK1 kinase in transgenic tomato lines OE-1, OE-3, and OE-4 was higher than that in the WT at different periods of fruit development; in the pink coloring period the SnRK1 kinase activity increased the most, with 23.5, 28.8, and 21.4% increases, respectively. The content of starch and soluble sugars in red ripe transgenic fruit significantly increased, while the soluble protein and titratable acid content decreased significantly. We also found that the tomatoes overexpressing PpSnRK1α matured approximately 10 days earlier than the WT. Moreover, the yeast-two-hybrid assay showed that PpSnRK1α interacted with the MADS-box transcription factor (TF) SIRIN, which acts as an essential regulator of tomato fruit ripening. The BiFC technology further validated the location of the PpSnRK1α interaction sites within the nucleus. The quantitative real-time PCR analysis showed that RIN expression was up-regulated by PpSnRK1α overexpression; the expression of RIN-targeted TF genes NOR and FUL1 increased during different stages of fruit development. The expression of key genes, ACS2, ACS4, and E8, in ethylene synthesis also changed accordingly, and the ethylene emitted by the red ripe fruit increased by 36.1–43.9% compared with the WT. These results suggest that PpSnRK1α interacts with SIRIN, increasing the expression of RIN, thereby regulating the expression of downstream ripening-related genes, finally promoting fruit ripening.

Flowering time determines the weight and composition of Actinidia chinensis var. chinensis ‘Zesy002’ kiwifruit

Consistently high flavour in fruit of a recently released commercial gold-fleshed kiwifruit cultivar ‘Zesy002’ is important for consumer acceptance. We hypothesised that variation in fruit weight and quality was determined during flower differentiation, and that date of flower opening and flower type (terminal or lateral) were important indicators. We determined whether time of flowering (early 5% open, mid 50% open and late 95% open) and flower type (terminal or lateral) influenced fruit weight, fruit maturity and fruit composition over two growing seasons. Fruit that developed from early-opening terminal flowers were 12–13 g heavier than those that developed from late-opening terminal flowers. Measurements in the second season suggested that this difference in fruit weight was related to ovary weight. Early-opening flowers were produced on shoots from smaller diameter canes than mid- and late-opening flowers. The soluble solids content, firmness and flesh colour of fruit was related to the period of fruit development, so late-opening flowers produced less-mature fruit as kiwifruit are harvested at a single date. Early-opening terminal and lateral flowers had significantly more outer pericarp tissue than fruit that developed from late-opening terminal flowers. This difference in tissue proportion was associated with 1–2 units higher fruit dry matter content and higher sugar:acid ratios in ripe fruit juice. Fruit from early-opening lateral flowers were smaller but had similar maturity and sugar:acid ratios to fruit from early-opening terminal flowers. These results suggest that competition during flower differentiation in spring influences the weight and composition of the ovary and fruit attributes at harvest. Hence, these attributes of ‘Zesy002’ fruit could be managed by manipulating flower development in spring.

Development and applicability of GBS approach for genomic studies in Japanese plum (Prunus salicina Lindl.)

ABSTRACTGenotyping by sequencing (GBS) provides a large quantity of useful data suitable for the identification of single nucleotide polymorphisms (SNPs), facilitating accurate genomic studies in plant species. In this study, GBS-based SNPs were used to characterise 11 Japanese plum cultivars and to explore their natural allelic diversity in relation to the most important phenology events (flowering date, ripening date and fruit development period) and fruit quality traits (weight, shape, skin and flesh colour, over colour, skin and flesh chlorophyll index, flesh firmness and soluble solids concentration). GBS-based SNPs were shown to be a powerful tool for genetic diversity and other genomic studies where SNP markers were related to several traits, particularly for flowering date, ripening date, fruit development period, skin chlorophyll degradation, flesh chlorophyll degradation and flesh colour. These results represent a preliminary approach using GBS as a possible breeding tool in current and new Japanese plum breeding programmes.

Effect of fruit-set time on the quality performance of Anona cherimola Mill. fruit in south italy

The aim of this work was to analyse the differences between fruits obtained by different dates of fruit set and identify the proper fruit-set time that allows to obtain the optimum fruit quality in Annona cherimola cv Fino de Jete, planted in Southern Italy. Six fruit-set dates were selected from the first week of June to the second week of July. Fruits were sampled from October to November, when 1500 Growing Degree Days (DD) were accumulated; The DD were calculated using a base temperature of 12 °C. Fruit fresh weight (FW) and skin colour were measured. These parameters were measured also after storage, and in addition, the following parameters were measured: fruit shape (FS), pulp colour, pulp firmness, number of seeds, total soluble solids content (TSSC), titratable acidity (TA), ascorbic acid (AA), total polyphenol content (TPC), total antioxidant capacity (TAC) and fruit dry weight (DW). Moreover, fruit dry weight percentage, fruit fresh weight loss (FWL), and the seed index were calculated after storage.The fruit development period changed from 120 to 146 days with the fruit-set date. The average seed number decreased with fruit set date. A strong correlation between fruit size and seed number occurred and also between the H/D ratio and number seed. FW decreased significantly from the third week of October to the first week of December and FS became progressively less regular in fruit coming from the 4th week of November to the 2nd week of December. From second to five sampling the AA was highest and similar. The lowest values of TAC were measured in the November and early December. The correlation between TAC and AA was stronger compared to TAC and TPC. All quality parameters of Annona cherimola fruit have reached the standards required by the market when 1500 DD have been accumulated from fruit-set. Eventually, the optimal period for fruit set ranged from end of June to the beginning of July.

Foliar application of potassium-based fertilizer improves strawberry fruit quality

Among the different mineral nutrients, potassium (K) is recognized as the macronutrient that most strongly affects the quality parameters of crops. An adequate K nutrition is in fact associated with increased fruit size, enhanced nutraceutical properties (e.g., content of sugar, organic acids, antioxidants), improved color and increased shelf life for many agricultural products. Previous studies have shown that, in controlled conditions, the foliar application of K-based fertilizers during the fruit development period could improve fruit quality; however, it is not clear whether such positive results can also be obtained in field-cultivated plants. For these reasons, the aim of the present study was to assess if the repeated applications of K-based fertilizers during the production period (mid-June to late August) might affect the quality parameters of strawberry (Fragaria × ananassa 'Murano') fruits. Frigoplants, transplanted in April, were cultivated in grow bags on cocopeat (8 plants per linear meter) and treated foliarly spraying K(2)SO(4) (6 g L(-1)) either once or twice a week. Control plants were sprayed with distilled water. As expected, foliar K-fertilization increased the K concentration by 8-11% in fruits and by 7-5% in leaves according to the frequency of application (once and twice a week, respectively). In addition, strawberry fruits exhibited an enhanced total soluble solids content (approximately 12%) and sweetness index (approximately 13%). Conversely, other nutraceutical compounds (e.g., phenolics, flavonoids and flavonols) as well as the fruit yield were not affected by K treatments, regardless the fertilization levels. In conclusion, results here presented show that at the field scale the foliar K-fertilization during the development of strawberries can enhance the quality and the nutraceutical value of fruits.

Cloning and expression analysis of the phytoene synthase gene in ‘Granny Smith’ apple (Malus × domestica Borkh.)

Phytoene synthase (PSY) plays a key role in the biosynthesis and accumulation of carotenoids as the first rate-limiting enzyme in the plant carotenoid pathway. In the present study, the ‘Granny Smith’ apple PSY gene, MdPSY, was cloned using in silico cloning. The length of the MdPSY was 1500 bp, which included a complete open reading frame of 1194 bp, encoding a predicted protein of 397 amino acids. Sequence analysis revealed that the ‘Granny Smith’ apple PSY protein shared high homology with MdPSY2 (99%), MdPSY1 (93.9%), FaPSY (71.8%), CuPSY (70.7%) and NtPSY (69.7%). Phylogenetic analysis showed that the MdPSY protein was closely related to the PSY protein of Rosaceae. An expression profile analysis of different tissues indicated that MdPSY expression in the roots was higher than that in other tissues. MdPSY expression was tested throughout the fruit development period. The results showed that MdPSY plays a role in carotenoid biosynthesis in ‘Granny Smith’ apple. In addition, bagging treatment inhibits PSY gene expression, which in turn affects the synthesis and accumulation of carotenoids.

Breeding of a fine apricot cultivar, ‘Xiajin’, for protected cultivation

‘Xiajin’ is an early maturing apricot cultivar suitable for protected cultivation. It was selected from seedlings of ‘Jintaiyang’ with desirable traits. Under greenhouse conditions, ‘Xiajin’ flowered 3-5 days later than ‘Jintaiyang’. However, ‘Xiajin’ has a short fruit development period (58 days). The fruits matured approximately 7 days earlier than those of ‘Jintaiyang’. The average fruit weight of ‘Xiajin’ was 90.42 g, which is 22 g greater than that of ‘Jintaiyang’, and the weight of its biggest fruit was 114.7 g. The dormant period of ‘Xiajin’ is very short, with a very limited chilling requirement. A low temperature treatment at ≤7°C for 400 h terminated dormancy and initiated blooming and normal fruit bearing. The percentage of full flowers, with pistils either longer than or equal in length to that of the stamens, was over 90%, whereas those with pistils shorter than stamens or degraded stamens was lower than 10%. After planting, the fruit yield of individual trees in the fifth year was 5.6 kg, equivalent to 940.8 kg mu‑1. In the sixth year, the density of trees was adjusted to 168 trees mu‑1. From the sixth to the eighth year, the fruit yield of individual trees stabilized at 8.99 kg, corresponding to 1510 kg mu‑1 and 30,200 RMB yuan output value. Grown in greenhouses in Yuncheng district of Shanxi Province, the cultivar can completely avoid the effects of late frost and other natural disasters and realize stable and efficient production and, therefore, it is a promising greenhouse-grown apricot cultivar.

Avocado fertilization: Matching the periodic demand for nutrients

Abstract The main objective of this study was to assess the seasonal nutrients requirement of ‘Hass’ avocado trees grown in lysimeters, especially during flowering and the early period of fruit development that may affect later on the fruitlet abscission and determine crop yield. The experimental design included three fertigation treatments applying a fixed nutrient solution at three different starting dates of fertigation: (a) T1 – continuous fertigation, including macro nutrients (N-P -K) and micronutrients application, all over the year; (b) T2 – no fertilization (only irrigation) until 15 March, and fertigation as T1 since then; (c) T3 - no fertilization (only irrigation) until 15 May, and fertigation as T1 since then. Absence of fertilization during the winter period induced leaf-chlorosis while healthy, dense and plenteously green leaves characterized the fertilized trees (T1). The beneficial effect of early fertigation on fruit yield was statistically significant, mostly because of higher fruit number. Leaf analyses are commonly used in the avocado industry as a guide for fertilization yet; fruits rather than leaves are the main products of avocado orchards. Consequently, fruit rather than leaf analyses should determine fertilization management. Based on fruit growth data and nutrient concentration in the fruit, the N, P and K quantities removed by ‘Hass’ avocado fruit yield of 30 t ha−1 were 120, 25 and 240 kg ha−1. Taking into account common efficiency consideration (nutrient quantities removed by fruit yield divided by quantities added), the annual quantities of N, P and K required for attaining high quality avocado yield are 250–300, 80–120 and 500–600 kg ha−1, respectively. Thus, fertilization rate together with nutrient combination should be modified in order to insure optimal fruit development.